Machine and method for dielectrically embossing trim strip material



June 13, 1961 B. E. KEVELIN ET AL 2,988,129

MACHINE AND METHOD FOR DIELECTRICALLY EMBOSSING TRIM STRIP MATERIALFiled March 5, 1958 6 Sheets-Sheet 1 UPPER D/E' GEN. l

LVVENTORS Brace ere/m,

ATTORNEY June 13, 1961 B. E. KEVELIN ET AL 2,938,129

MACHINE AND METHOD FOR DIELECTRICALLY EMBOSSING TRIM STRIP MATERIAL 6Sheets-Sheet 2 Filed March 5, 1958 .5... .vv o M (Q o 0 0 O O 0 0 0 L 5?251. 5

June 13, 1961 B E. KEVELIN ETAL 2,988,129

MACHINE AND METHOD FOR DIELECTRICALLY EMBOSSING TRIM STRIP MATERIAL 6Sheets-Sheet 3 Filed March 5, 1958 IVVE/VTORS J3 z zzce 6161 6/ 2; B)790 6 380256;, /@'Q 7 Joseph ll/aad 'azz/ [/1 /e/% A 7'7'ORNEY June 13,1961 E. KEVELIN ET AL 2,988,129

MACHINE AND METHOD FOR DIELECTRICALLY EMBOSSING TRIM STRIP MATERIALFiled March 5, 1958 6 Sheets-Sheet 4 I g [N VEN T0 R5 June 13, 1961 B.E. KEVELIN ETAL MACHINE AND METHOD FOR DIELECTRICALLY EMBOSSING TRIMSTRIP MATERIAL 6 Sheets-Sheet 5 Filed March 5, 1958 2 A TTORNEY June 13,1961 B. E. KEVELIN ETAL MACHINE AND METHOD FOR DIELECTRICALLY EMBOSSINGTRIM STRIP MATERIAL 6 Sheets-Sheet 6 Filed March 5, 1958 INVENTORS IEzzzce d'z/eAw a C7, @6027, p); Zbadzozy w/ezz w 5 My u m M U flaw "m"fiw/ w rm 1.3 .U 1., M w n VI 2,988,129 Patented June 13, 1961 2,988,129MACHINE AND METHOD FOR DIELECTRICALLY EMBOSSING TRIM STRIP MATERIALBruce E. Kevelin, Detroit, Ted A. Redo, Birmingham, and Joseph WoodrowWillett, Harper Woods, Mich, assignors to General Motors Corporation,Detroit, Mich., a corporation of Delaware Filed Mar. 5, 1958, Ser. No.719,438 11 Claims. (Cl. 154--1.6)

The present invention relates to a method and appara tus for joiningdecorative strips to a sheet material for use as interior trim inautomotive vehicles. While the embellishment of such trim materials forautomobile interiors represents an important application of the subjectmethod and apparatus, it will be apparent that the invention has generalutility wherever decorative trim materials are employed.

While it is generally old to emboss or bond one trim material uponanother, no method or apparatus has been available whereby this may bedone fast enough for use with products being made on assembly linebasis. In the present invention a method and apparatus has beendeveloped which permits such trim panels to be embellished withdecorative strips at rates consistent with assembly line operation andat a cost not substantially greater than non-decorated trim panelspreviously used.

There is increasing demand to provide trim sheets or panels havingdecorative designs or highlighted materials formed thereon and furtherwhich decorated trim panels are capable of being fabricated intodiiferent, including three dimensional shapes after the decoration orembellishment has taken place. These demands have not been satisfied bypreviously known methods of fabricating trim panels which most commonlyhave included embellishing a sheet or trim panel by securing a rigidtrim or strip material thereto by means of a clip or other mechanicalclamping devices. It is apparent that the use of such rigid trim stripsconsiderably limits, both physically and economically, the extent towhich such trim strips may be utilized. The present invention, on theother hand, represents a significant contribution in that it permits theuse of flexible thermoplastic trim strip materials dielectricallybondable or embossable upon a sheet of similarly thermoplastic materialin a way which permits the composite to be subsequently fabricated intoinnumerable forms. Thermoplastic materials refer to any heat softenablematerials and are not limited to plastic substances.

The subject method and apparatus permits one or more trim strips to befed along a die member where a finite length of such material is cut offand clamped to the die. Thereafter the sheet material to be decorated isbrought into proximity with the strip material following which the trimstrip and sheet material are dielectrically heated bonding or embossingthe strips upon the sheet material.

Working with relatively narrow, but aesthetically desirable, trim stripscreates many problems particularly where it is desired to simultaneouslywork with a plurality of such strips and to dielectrically bond oremboss the same to a trim sheet at assembly line rates. It is thepurpose of the present invention to provide an apparatus which isuniquely able to permit such embossment. Inasmuch as it is an object ofthe present invention to provide an apparatus capable of working with aplurality of these narrow trim strips and further in which it is desiredto work with finite lengths of such materials, a unique feedingmechanism has been provided which is capable of grasping a plurality ofsuch strips moving the same into position on a die member where thestrips may be clamped and cut to the appropriate length prior todielectric embossment and after which embossment the feeding mechanismmay repeat the cycle.

The use of narrow trim strips creates a further problem of providing asuitable die member which is capable of maintaining the strips in theproper position preliminary to as well as during the bonding orembossing steps. The subject die is not only capable of guiding the trimstrips, as proposed, but is also uniquely constructed in a mannerpermitting the guiding structure to be moved to a noninterferingposition during the actual bonding or embossing step. It is still afurther object to provide such a die mechanism which is uniquelyconstructed to permit an optimum electrical field to pass through thetrim strip material to achieve proper dielectric bonding without thelikelihood of arcing to which such narrow trim strips are otherwisehighly susceptible.

Other objects and advantages of the present method and apparatus will beapparent from a perusal of the detailed description which follows.

In the drawings:

FIGURES 1-3 are diagrammatic showings of the subect apparatus;

FIGURE 4 shows a sheet having a decorative trim strip bonded thereto;

FIGURE 5 is a plan view of the subject apparatus;

FIGURES 6 and 7 are enlarged detail views of the carriage clamping head;

FIGURE 8 is an enlarged elevational view of the carrrage;

FIGURE 9 is a view along line 9-9 of FIGURE 8;

FIGURE 10 is a view along line 10*10 of FIGURE 9;

FIGURE 11 is a view along line 11-11 of FIGURE 8;

FIGURE 12 is a partial isometric view of the lower die;

FIGURES l3 and 14 are fragmentary sectional views showing upper andlower die coaction; and

FIGURE 15 is a fragmentary enlargement of the embossing blade.

Referring to FIGURES 1 through 3 of the drawings, a schematicrepresentation of the subject apparatus is shown and includes adielectric press 10 which includes a lower die member 12 and an upperdie member 14. One of the die members is movable relative to the otherin order that the dies may be positioned in proximate or embossingrelation. For illustrative purposes, upper die 14 may be consideredvertically movable with respect to lower die 12.

A high frequency generator is shown generally at 16 and is adapted tocause an alternating current to flow between the dies when dielectricheating is desired. The theory of dielectric heating and embossing isset forth in considerable detail in prior patents and other literatureon subject. For present purposes, it should sufiice to note that when ahigh frequency alternating current is passed through a suitablethermoplastic material, molecular heating takes place which enables suchmaterial to be embossed or bonded to another similarly heated material.The dielectric press, per se, forms no part of the present invention.

Trackways 20 are formed on either side: of the lower or fixed die 12 andare adapted to support a carriage 22 for movement relative thereto.Carriage 22 includes a clamping head indicated generally at 24 adaptedto clampingly engage a plurality of strips of thermoplastic material 26wound respectively on spools 28. Spools 28 are rotatably mounted upon asupport bracket 30. After the carriage head 24 has clampingly engagedthe trim strips 26, infra, the carriage is adapted to be movedleftwardly in trackways 20 feeding out and positioning the strips withinaligning and embossing grooves 32 in lower die member 12. After carriage22 has moved a sufficient distance to lay trim strips 26 throughout thelongitudinal length of the die grooves 32, clamping or tensioning arms34 and 36 pivotally mounted at 38 and 49 upon die supporting structure42 clamp the strips upon the die and simultaneously cut off the stripsfrom both the rolls 28 and from the clamping head 24. Thereafter a sheetof thermoplastic material 44 is brought into an overlaying position withrespect to said strips, as best seen in FIGURES 13-15, and die member 14moved toward lower die 12 to clamp the assembly together. Thereafter thehigh frequency generator is energized dielectrically bonding strips tothe sheet material. A pair of rubber pads 46 are disposed between sheet44 and die 14 to prevent arcing during dielectric heating. After thedielectric embossment step the trim sheet or panel is removed from thedie and the carriage member returned to its starting position where itis again prepared to clampingly engage the trim strips to repeat the ccle.

The various components of the subject apparatus will now be consideredin greater detail.

Carriage The carriage 22 is shown in greater detail in FIGURES 6 through8 to which reference is now made. While the actual construction of thecarriage may take any number of forms, a preferred embodiment utilizes arod or tubular construction as shown. A pair of transverse rods 50 haverollers or wheels 52 formed respectively at the ends thereof and whichrollers are disposed in trackways 20. Rods 50 are reinforced by rods 51and 53. There appears to be no practical limit to the size of carriage22 the dimensions of which will be determined in general by the width ofthe material to which the trim strips are to be embossed.

The size of clamping head 24 is also a variable depending on the numberof trim strips with which it is desired to work. A single large clampinghead might be used which was capable of pulling a large number of trimstrips or as is the case with the apparatus illustrated, a plurality ofsuch heads may be used, the precise number again being determined by thenumber of strips to be embossed. While the means for so doing is notshown, it is to be understood that the clamping heads may be adapted tobe moved transversely of the carriage depending on the desireddisposition of the strips on the sheet material. Clamping head 24includes a supporting block 54 suitably mounted upon transverse rod 56.A rake-like member 56 is supported from the bottom of supporting block54 and extends forwardly therefrom in the direction of the strip rolls28. Member 56 has a downwardly offset portion 58 formed at one endthereof and which portion terminates in a plurality of forwardlyextending fingers 60. A similar member 62 is pivotally supported by pin64 on block 54 in vertically spaced relation to member 56. Block 54 isactually recessed at 66 permitting member 62 to rotate about its pivot.Member 62 also includes a downwardly extending portion 68 terminating ina horizontal lip 70. A plurality of members 72 corresponding in numberto and aligned with fingers 60 of member 56 are dependingly supportedfrom lip 70. Members 72 are formed of hardened steel preferably mountedto lip 70 upon suitable resilient pads 73 to cushion the engaging actionbetween members 72 and fingers 60.

A U-shaped spring member 74 is disposed within the recessed portion 66of block 54 so as to normally bias the pivoted member 62 in an upwardlyor counterclockwise direction away from the fixed member 56. A lever 76is pivotally supported in block 54 upon pin 78 above the pivoted member62 and is adapted when rotated in a clockwise direction to its verticalposition, as shown in FIGURE 8, the pivot cam against member 62 rotatingthe latter in a downwardly direction whereby the resilient members 72engage fingers 60 of member 56.

Strip flow restrictor Referring momentarily to the trim strip feedingapparatus, it will be noted that the strip materials 26 from the variousrolls 28 are fed through a strip flow-restrict ing device indicatedgenerally at 80. The flow restrictor 80 includes a block member 82having a plurality of openings 84 formed therethrough and correspondingin number to and axially aligned with die grooves 32. A verticallyadjustable stud 86 is arranged to project toward each strip opening 84.A pad 88 which is noninjurious to strip 26 is mounted upon the lower endof stud 86 for relatively light frictional engagement with the stripproviding a variable resistance to the flow of the strip materialtherethrough. The purpose of device 80 is to insure that the trimmaterial will remain under tension as carriage 22 draws the same overthe die 12. In this way the strip segments will be under tension whenthe clamping or tensioning bars 34 and 36 clamp the strips to the die.By maintaining strips 26 under tension it insures that there will be nowrinkling and further that there will be intimate engagement between theembossing dies and the material. It is apparent that the amount oftension on the trim strips may vary by adjusting the studs 86.

An L-shaped plate or lip 90 is clamped to flow restrictor block 82 forsupporting the terminal ends of the trim strips whereby the latter maybe presented to the clamping head 24 of carriage 22 in a substantiallyhorizontal attitude.

The trim strip clamping operation is as follows: the clamp actuating arm'76 is pivoted to the dotted position shown in FIGURE 8 which permitsthe spring 74 to open members 56 and 62. Thereafter, carriage 22 ismoved in the direction of the trim rolls 28 which ultimately results inthe front wheels of the carriage dropping into a downwardly inclinedportion 92 of the trackways 20. This permits the fixed clamping member56 to pass underneath the strip supporting lip 96. The movement of thecarriage is limited by stop members 94 formed of any suitable materialsuch as hard rubber. In this position of the carriage the members 72 andfingers 60 are aligned on opposite sides of lip 99. Next, clamping lever76 is rotated to its vertical position moving the resilient members 72into engagement with strips 26 supported on lip 90. Carriage 22 now ismoved to the left causing strips 26 to be clamped between fingers 6i)and resilient members 72. Continued leftward movement of the carriagefeeds the respective strips through the corresponding embossing grooves32 formed in die 12. The carriage continues to traverse the trackways 20in a leftwardly direction until the rear wheels thereof engage stops 96suitably longitudinally spaced from the die I2 to permit the embossinggrooves to be completely overlaid with the strips 26.

It is to be understood that the movement of lever 76 as well as carriage22 itself may be accomplished either manually or automatically. Tosimplify the illustrated embodiment of the present invention theapparatus is shown as manually operable.

Tensioning and cutter devices With the carriage in the position as thusfar described, trim strips 26 will have passed tensioning and cutterdevices indicated generally at -98 and 100. The tensioning and cutterdevices are mounted on the die supporting structure 42 proximate eitherend of die 12 and extend transversely thereof. Since they are identical,it will only be necessary to describe one set of the devices. Device 100includes a fixed or female member Th2 mounted directly on the diesupporting structure and arm 36 pivotally supported upon a bracket 104.When the die is being loaded with trim strips the pivoted arm 36 isadapted to be rotated to an upwardly position, shown in FIGURES l and 2permitting traversal of the die by carriage 22. With the carriage in itsleftmost position, however, arms 34 and 36 are pivoted toward the fixedsupporting member 102 clamping the trim strips between itself and thesupporting member. To provide clamping engagement between the members 36and 102, they have been shown tapered in cross section, see FIGURE 10.It is also possible to utilize a square or rectangular cross section formembers 36 and 102 if desired.

A cutter bar 106 is fixed to the pivoted arm 36 so that as the arm isrotated and has clamped the trim strips to the member 102, the finalmovement of the arm will cause the cutter bar to cut off the trim stripsintermediate clamping head 24 and the flow-restricting device 80. Asimilar cutting device and operation obtains with respect to arm 34.

A pair of tensioning and cutter devices is normally provided for eachcutting head, therefore, in the illustrative embodiment a pair ofclamping and cutting devices 98' and 100' is provided for coaction withclamping head 24'. Since locking devices 98- 18 and 100100 are axiallyaligned, as shown in FIGURE 5, it is possible to use single tensioningarm locking members -108-110 at each end of die 12. As seen in FIGURE 9,locking member 108 includes an arm 112 pivotally mounted on stud 116.Arm 112 is resiliently urged in a clamping direction by a spring 114.Arm 112 is rotated to release clamping devices 100100'.

At this point the trim strips have been severed from the carriage 22 andthe rolls 2 8 and are retained under tension within the die grooves 32in condition for bonding and embossment to the appropriate thermoplasticsheet material 44.

Before proceeding further with a description of the apparatus it is wellto consider the manner in which the sheet material 44 may be presentedto the lower die member 12 and trim strips 26. As best seen in FIGURE13, silicone rubber pads 46 are loosely disposed intermediate sheet 44and the upper die 14 in order to prevent arcing between the die membersand the thermoplastic materials involved. In this type of arrangementthe trim strip material is embossed upon the sheet 44, see FIGURE 4,leaving the latter in a flexible condition to permit its beingfabricated into any desired form.

Die construction A most important part of the subject apparatus is thelower die 12 and the manner in which the same is constructed. Referringparticularly to FIGURES 12 through 15, it will be appreciated that thedie is built up of a plurality of components. A plurality of aligned andtransversely spaced embossing blades 116 are suitably fixed tosupporting plate 42. The embossing dies are of L- shaped cross sectionto provide a rigid support. The embossing ends 129 of blades 1 16 are ofan arcuate, al though optional, shape to provide the appropriateembossed contour of the trim strips 26 on sheet 44. In order that thetrim strips be properly guided into superadjacent alignment with theembossing blade when the carriage device feeds the strips to the lowerdie, guide plates or guide members 122 are provided on either side ofeach blade. At least a portion of the guide plates is adapted to bevertically positioned above the embossing blades to an extent sufficientto cooperate with the blades to define therewith the die grooves 32 intowhich the trim strip is fed by the carriage mechanism.

However, while the guide plates are necessary for properly positioningthe trim strips with respect to the embossing blades, it is equallynecessary that these plates be depressed or retracted so as not tointerfere with the dielectric bonding and embossing step. To this end,guide plate supporting channels 124 are provided adjacent the embossingblades 116 and secured to support 42 through studs 118. In order thatthey may be retracted during the embossing step, however, the guideplates are mounted upon resilient pads or strips 126. Pads 126 may heformed of any suitable. resilient material such as rubber ordi-isocyanate foam.

Earlier modifications of the die mechanism utilized guide plates formedof non-conductive substances such as wood which, however, proved tocontribute to unsatisfactory embossment. The unsatisfactory embossmentwas traced to several factors all of which were eliminated by formingthe guide plates of a metallic material and shaping the plates so as toprovide the ridges or lips 128 at the outer edges thereof.

Previous to the present die construction, it was found that the fieldintensity was increased at the edges of the embossing blades and trimstrips due to their sharp edges. The result was, of course, voltageconcentrations and periodic discharges along these edges burning orscarring the thermoplastic materials. The field intensity concentrationwas also enhanced by the fact that non-conductive materials, e.g. woodguide plates, were disposed between the respective embossing bladescausing all. stray flux lines to pass through the nearest conductor, inthis instance, the embossing blades.

In the present modification, however, the metal guide plates 122 aremaintained at the same potential through contact strips 130 as theembossing blades. Likewise, guide plate elevation is maintainedsubstantially equal to that of the embossing end of the blades. Theguide plate elevation actually refers to the ridges or lips 128 which,as seen in FIGURE 15, are flush with the embossing edge 120 when theplates are depressed during embossing. In this Way the electric fieldbetween die 14 and the embossing blade 116 is more uniformly distributedgreatly reducing the field intensity at the edges of the trim strip andresulting in better overall embossment. This demonstrably betterembossment is attributed, at least in part, to the fact that stray linesof flux tend to be collected by the guide plate lips 128 rather than bythe embossing blade edges as in the past.

The embossing blade voltage is transmitted to each guide plate 122through copper contact strip 130. Contact strip 130 is fixed at one endto supporting channel 124 through stud 118. The other end of the contactstrip is fastened to the guide plate through a screw 132. The embossingblade voltage is thus transmitted through the short leg 134 of channel124 which rests upon the horizontal leg 136 of the embossing blade.

It is apparent that various modifications may be made in the illustratedembodiment of the present invention within the scope of the appendedclaims.

We claim:

1. A dielectric bonding and embossing apparatus comprising relativelymovable die members, means for passing a high frequency alternatingcurrent between said die members, an embossing blade formed on one ofsaid die members, means for drawing a strip of thermoplastic trimmaterial across said one die member in superadjacent alignment with saidembossing blade, means for cutting and clamping a finite length of saidstrip in supported relation upon said blade, whereby the strip ispositioned for bonding to a sheet of thermoplastic material, said onedie member also including guide members for maintaining the strip inalignment with the embossing blade, and means for maintaining said bladeand guide members at the same voltage.

2. A dielectric bonding and embossing apparatus as set forth in claim 1in which means is provided for resiliently supporting said guide membersupon the die member whereby the guide members are depressed to exposethe embossing blade during the bonding operation.

3. A dielectric bonding and embossing apparatus as set forth in claim 1in which the strip drawing means comprises a carriage movable relativeto said dies, the carriage including a head having a device forclampingly engaging and retaining said strip whereby the strip isadapted to be drawn across the embossing blade as the carriage is movedrelative to the dies.

4. A dielectric bonding and embossing apparatus comprising a pair ofrelatively movable die members, means for passing a high frequencyalternating current between said die members, an embossing blade formedon one of said die members, means for drawing a strip of thermoplastictrim material across said embossing blade to longitudinally support saidstrip upon said blade, means for maintaining said strip under tensionWhen being drawn across said embossing blade, guide memberslongitudinally coextensive with and abutting said embossing blades andvertically adjustable with respect thereto, means biasing the guidemembers in a vertically extended position whereby said guide members andsaid embossing blade coact to define a trim strip guiding groove, meansfor maintaining a finite length of said trim strip under tension withinsaid groove such that said trim strip can be dielectrically heated andbonded to a sheet of thermoplastic material disposed between said stripand the other of said die members upon movement of said die members onetoward the other, the movement of said die members being adapted todepress said guide members to eliminate the trim strip guiding groove.

5. An apparatus as set forth in claim 4 in which the strip drawing meanscomp-rises, trackways disposed on opposite sides of the embossing bladesupporting die, a carriage movably mounted upon said trackways, saidcarriage including a clamping device having a first element rigidlyfixed to the carriage, a second element pivotally mounted relative tothe first element, means controlling the pivotal movement of said secondelement, said tension maintaining means including a ledge member forsupporting said strip proximate one end of the embossing bladesupporting die, said trackways having depressed portions adjacent saidledge member, at least part of said carriage being movable into thedepressed portions of said track- Ways permitting the first element ofthe clamping device to be disposed below and the second element abovesaid ledge member to position said elements for clamping engagement withsaid strip.

6. A dielectric bonding and embossing apparatus comprising a pair of diemembers, means for passing a high frequency alternating current betweensaid members, one of said die members including a blade having an outerembossing surface facing the other die member, metal members disposed onlaterally opposite sides of said blade in abutting relationshiptherewith each having an outer elongated ridge portion coextensive withsaid blade and facing the other die member, said metal members beingdepressible with respect to said blade, and means for biasing said metalmembers into an extended position with respect to said blade wherebysaid metal members and said blade define a guide groove adapted tosupport a strip of thermoplastic material therewithin, one of said diemembers being movable toward the other to thereby depress said metalmembers and expose said strip of thermoplastic material for bonding toanother body of thermoplastic material, the ridge portions of said metalmembers having a rounded contour to reduce voltage concentration at theedges of the embossing blade during said bonding.

7. A dielectric bonding and embossing apparatus com prising a pair ofrelatively movable die members, means for passing a high frequencyalternating current between said die members, one of said die membersincluding a blade having an outer embossing surface facing the other diemember, guide members disposed on laterally opposite sides of said bladein abutting relationship therewith and having outer surfaces coextensivewith said embossing blade and facing the other die member, said guidememhers being depressible with respect to said blade to a positionwherein the outer surfaces of said guide members are generally flushwith the embossing surface of said blade, and means for biasing saidguide members into an extended position with respect to said bladewhereby said guide members and blade define a guide groove adapted tosupport a body of dielectrically bondable material therewithin, therelative movement of said dies being adapted to depress said guidemembers during dielectric bonding.

8. A dielectric bonding and embossing apparatus comprising a pair ofrelatively movable die members, means for passing a high frequencyalternating current between said die members, one of said die membersincluding a blade having an outer embossing surface facing the other diemember, metal members disposed on laterally opposite sides of saidembossing blade in abutting relationship therewith each having an outerelongated raised edge surface adjacent said blade and facing the otherdie member, said metal members being depressible with respect to saidblade to a position wherein the outer raised edge surfaces of said metalmembers are generally flush with the embossing surface of said blade,and means for biasing said metal members into an extended position withrespect to said blade whereby said metal members and said blade define aguide groove adapted to support a body of thermoplastic materialtherewithin, the relative movement of said dies being adapted to depresssaid metal members to expose said body of material for bonding toanother body of thermoplastic material.

9. An apparatus as set forth in claim 8 and including means formaintaining said blade and said metal members at the same potential withrespect to the other die member.

10. Apparatus as set forth in claim 8 wherein each of the raised edgesurfaces of said metal members is in the form of a ridge having arounded contour so as to reduce the voltage concentration at the edgesof the embossing blade during the dielectric bonding.

11. A dielectric bonding and embossing apparatus comprising a pair ofrelatively movable die member, means for passing a high frequencyalternating current between said die members, one of said die membersincluding a blade having an outer embossing surface of concave contourfacing the other die member, metal plate members disposed on laterallyopposite sides of said blade in abutting relationship therewith eachhaving an outer convex rounded edge surface adjacent said blade andfacing the other die member, said plate members being depressible withrespect to said blade to a position wherein the edge surfaces of saidplates are generally flush with the embossing surface of said blade, andresilient members under said plate members to bias said plate membersinto an extended position with respect to said blade whereby said platemembers and blade define a guide groove adapted to support a body ofthermoplastic material therewithin, the relative movement of said diesbeing adapted to depress said plate members to expose said body ofthermoplastic material for bonding to another body of thermoplasticmaterial.

References Cited in the file of this patent UNITED STATES PATENTS492,116 Smith Feb. 21, 1893 945,249 Shields Jan. 4, 1910 2,371,847Saunders Mar. 20, 1945 2,573,466 Lyijynen Oct. 30, 1951 2,758,631Peterson Aug. 14, 1956 2,804,419 De Woskin Aug. 27, 1957 2,822,454Rothstein Feb. 4, 1958

